NASA used numerous telescopes to scan an object called 2014 MU69, an extremely unusual red object, about 1 billion miles beyond Pluto. The object has a diameter of about 30 miles and orbits the sun once every 293 years, which meant the space agency could only study it during a two second period when it briefly crossed in front of a distant star.
Observations of MU69 could only be made from an extremely limited area on Earth that included Argentina and South Africa. Researchers drafted more than two dozen fixed telescopes for the project and were able to set up 25 portable telescopes in the viewing area in time.
The feat was “the most technically challenging and complex stellar occultation observation campaign ever attempted,” according to the NASA statement.
NASA is sending the space probe New Horizons to MU69 on January 1, 2019. NASA’s Hubble Space Telescope discovered MU69 during a preliminary survey to find a suitable object for New Horizons to visit in 2014.
“The reddish colour tells us the type of Kuiper Belt object 2014 MU69 is,” Amanda Zangari, a New Horizons post-doctoral researcher from Southwest Research Institute, said in a NASA press statement. “The data confirms that on New Year’s Day 2019, New Horizons will be looking at one of the ancient building blocks of the planets.”
Scientists used New Horizons data to conclude the liquid ocean is probably water mixed with ammonia, which is similar to some commercial antifreeze. The liquid helps keep Pluto relatively warm. Other research using the probe suggests that Pluto is still expanding, meaning it probably has an ocean.
Other research recently used computer models of Pluto’s temperatures to determine that if the dwarf planet’s ocean froze millions or billions of years ago, it would have caused the entire planet to shrink. Pluto’s ocean is likely buried under a shell of ice more than 180 miles thick. The ice insulates the ocean enough to prevent it from totally freezing, effectively keeping the dwarf planet somewhat warm. The ocean could also be responsible for unusual geologic activity in Pluto.